Physicists! Help An Author to Wreck An Entire Continent Accurately!

One of the weirder aspects of writing novels is that eventually, you assemble a dream team of experts to consult. When I wrote Flex, which dealt with a severely burned girl, I consulted my friends MedKat and Cassie Alexander, both medical experts who helped me get the ICU details right.  When I wrote The Flux, which features a child with PTSD and a funeral, I consulted my friends Dr. Natasha Lewis Harrington (a child therapist) and Heather Ratcliff (a mortician) to get the details right.
Now, uh, I’ve kind of broken all of Europe and I need to talk to a physicist.
In case you’re unfamiliar with Flex, in it there are creatures called “Buzzsects” that devour our laws of physics – they eat the speed of light, change the rules of time, et cetera.  And now, I want to do some XKCD “What-if?” thought experiments to go, “What happens if the speed of light permanently drops to, say, 50 MPH in a ten-foot area?  What happens if we change the structure of an atom?”  And to explore that ensuing mayhem.
If you’re a) experienced with physics, and b) think this sort of “Remove one major law of physics, see how the rest of it collapses” thought experiment might be fun (with the caveat that story needs may trump precise accuracy), do me a favor and email me at theferrett@theferrett.com with the header “I AM WILLING TO WRECK EUROPE.”  For you, dear sir or madam, will be the one who helps me determine the fine details of how to savage an entire continent.
And really, how often do you get that opportunity?